A new HPA system for the KJW M700 - Still to be tested

[smjbmw]

Hey everyone

Ok so heres the deal. I got my m700 about a week or so ago and I am crazy over bolt action sniperrifles so for the price I could'nt say no.

I have yet to test this but have my adapter coming and will be testing this soon. I will post a video on my website so you can see how it turns out.

For people who dont know what an HPA system actualy is and are confused already. Well lets clear some of that up.

HPA is using high pressured compressed air to power your rifle. It is seen alot on other airsoft sites and can bring up the range and accuracy of the kj m700to a hole new level.

This use to require drilling out your mags adding a quick release hose attachment to your mags to hook up to a paintball feed line hooked up to a regulator, on off switch and a high pressure tank.

Well I have found a way to completely eliminate the manual labour and hard work and found a way that might make it so simple that people who have hpa systems will be very very pissed off

We have found an adapter much like propane adapters but for c02 and compressed air

You can buy a compressed air tank and attach it just like a propane adapter.
The new version of the adapter comes with a regulator attached that can range from 50 psi and up.

Propane runs around 100psi so what does this mean?

Compressed air is not effected by colder weather like propane is. It might make a bit of difference but nothing like propane or c02

Accuracy - I have read that some people are getting insane ranges with this method.

I ask that if you are going to try this that you be very very careful. You will e dealing with very high pressure not like just putting green gas in. If you are goign to try this please follow safe airsoft rules and wear eye protection.
And always always always follow strict field rules on FPS


We will be testing this in the upcoming weeks but feel free to leave comments

[MadMax]

Truth is that the KJW M700 can already exceed most field and even minimum firearms limits:

http://www.airsoftcanada.com/showthr...&highlight=kjw

A consistent regulated HPA setup could go far in improving shot to shot consistency (reducing cooldown related varation), but the stock M700 is already capable of becoming too powerful to field if one cranks up the adjustable bolt. I did not mess with my bolt before doing my FPS measurements. Tests were done on a factory built gun.

Unfortunately the M700 does not have a particularly consistent hop up design. For all of it's capacity for power, it does not translate into surprising accuracy. It also has a design flaw in the magazine design. The metal retention fingers at the top of the magazine often scratches the pellets as they are pushed into the breech by the bolt. This can result in bizzarre flyers. I have attempted to circumvent this issue by hand loading pellets into the breech so they don't get cut by the mag fingers. While the very crazy flyers are prevented, the net accuracy still isn't very impressive. I suspect that there may be an inconsistency in the way the hammer pin opens the magazine valve. It's also possible that the outlet port on the magazine does not provide a consistent seal against the bolt contributing to muzzle velocity variation.

WARNING: Do not exceed 160psi outlet pressure on your HPA rig. Even at 120psi, the KJW M700 can exceed minimum firearms limits (500fps AND 5.7J) with heavy rounds. However, it is doubtful that the cast metal magazines are carefully engineered to proof pressure standards. The metals used in airsoft often fail in brittle modes and are not particularly well suited to high pressure applications. If you insist on very high pressure use, you should proof test your system with your magazine and lines filled with incompressible liquid such as silicone oil or water. This is called hydrostatic testing. Proof your system to at least 3 times expected operating pressure. Do not proof test with gas filling your suspected pressure vessel as a ruptured vessel filled with high pressure gas fails VERY energetically. A vessel failing with an incompressible liquid fails rather benignly as the contents do not have a very high potential energy (like freezing water bursting a pipe), but expanding gas can propel shrapnel. If you are not directly experienced in hydrostatic testing you may not understand the hazards of it. Take your setup to a scuba shop which offers hydrostatic testing. They are used to testing very high energy pressure vessels.

[bean]

From the sounds of it your just using air to fill the mag. This would result in very few shots. The reason i say this is co2 and duster are liquids in the mag and allowed to expand. I think you would get maybe 4 shots before you noticed a major power drop.

[MadMax]

On re reading, it sounds like someone's discovered the MadBull pball tank regulator. Yeah, it regulates, but transfers no liquid so you end up with the situation which Bean suggests. Shot to shot performance will be even worse than 2 phase propane.

[CDN_Stalker]

Darkshadow is pretty much trying to make the gun more consistant shooter in various temps and NOT trying to make it more powerful. He's getting all info related to the KJW M700 from me, and he's aware the insane fps that can come from propane usage on hot days. Hell, my first shot on a +35C day with a fully filled mag (was these results that I discovered much improvement if the gun is dry fired 4 shots before loading BBs) was about 710fps with a 0.20g BB.

As far as the inner feed lips, yes they are sharp. I used a round diamond file to smooth the entire area of the feed lips and have zero problems now, I can slide the bolt forward with little resistance.

Accuracy, once the barrel was free floated (it was bent to keep it centered, it & Apoc's both sit slightly to the left now) and I cut two coils off the striker spring, the gun went from CD sized groupings at 30ft in my basement down to 10 shots into a loonie sized grouping. This gun also insists on a clean inner barrel, so I'll run a dry .22cal patch through it every 20-30 shots. Can also hit relatively consistanly pop cans out to about 100ft.

I found the hop up to not be all that great for heavier BBs, best I've found is the 0.30g weight and under.

[bean]

Go to the classic airsoft website and follow the rig guide and build a rig off of those specifications. You will need a second regulator hooked up to the hpa tank. You will likely have to drill the magazine unless you manage to find a qd fitting in that threading. Bring the fill valve with you to some local pneumatic parts shops easily found int he yellow pages. You might just luck out.

[CDN_Stalker]

Since I got home and was able to find out what type of diamond file I have, I figured it a good idea to show it here. I bought it at Le Baron for about $10.



I used that to file the sharp edges off my inner feed lips and the results were awesome. Incidentally, this tool is amazing for GBB mags as well. My KSC G19 mags had a hole a bit too small to be able to 'drop in' BBs to load it, often they'd have to be pressed in. I unscrewed the rat tail file from the handles, inserted the small end as far as I could into my electric drill, then quite literally drilled the hole between the feed lips of my G19 mags bigger. The large end of the file is 1/4", and the result is perfect, the BBs fall right in (I can use my BB loader alone and my thumb over the top and the BB go in very smoothly) and they stay in without any issues, and feed great now. Perfect for anyone with the same problem I had with their mags, as well as anyone who has dropped a mag and found it fell on the feed lips closing them up slightly.